She said she thinks MPs will rule out no deal on Wednesday night, and parliament would have to extend article 50 as a "natural consequence".
The revised agreement package, reached in Starsbourg on Monday evening, was rejected in the House of Commons by 391 to 242; its previous version was resoundingly voted down in January.
"We need to make a decision tonight and that has to be to let this deal pass".
Pressed on Labour's position on a second referendum she said: 'We have not ruled out a People's Vote but our priority is securing a deal'.
Brexit is set to happen on 29 March.
Simon Hart, the Carmarthen West and South Pembrokeshire Conservative MP, said: "Basically the result is that any outcome is now possible, from a deal to no deal, to a delayed deal, to the loss of the prime minister, to the loss of a government, to an election".
Amid speculation about how long she can survive in Downing Street, the Prime Minister's aides insisted she had not considered resigning.
European Commission Regrets UK Parliament's Brexit Vote Outcome - Statement
His advice suggests that many lawmakers who have opposed May's deal are unlikely to change the way they vote in Parliament later. With this latest defeat, there is more concern about whether Britain will end up with a no-deal Brexit on March 29.
So if MPs prefer an "orderly exit" over no-deal and no Brexit, they will eventually have to vote positively in favour of a deal.
Jeremy Corbyn said "maybe it's time we had a general election".
"You've got to be able to walk away in any negotiation process and if people aren't willing to do that then we can't negotiate".
There were 75 Tory rebels - down from 118 last time - as well as all 10 DUP MPs.
Under the no deal plan revealed this morning, 87 per cent of products would be subject to zero tariffs in an effort to stop price spikes and kick-start trade with Britain from across the world.
I am surprised it is a free vote.
Pro-EU Labour Cardiff Central MP Jo Stevens said: "You've got to wonder what more [Theresa May] could try and do".
Mr Corbyn said the Government needed to "accept their deal is clearly dead and does not have the support of this House".
Speaking in Strasbourg, where the European Parliament is gathering for a debate on Brexit ahead of the next European Council summit, the EU's chief negotiator Michel Barnier said: 'Again the House of Commons says what it doesn't want. The choice for Conservative Brexiteers will look much starker if the United Kingdom is in a position next week where parliament has rejected no-deal, and the European Union is offering a year-long delay to Brexit.